promql: error if all label matchers are empty.

promql/parse.go

@@ -883,6 +883,25 @@ func (p *parser) vectorSelector(name string) *VectorSelector {
 	if len(matchers) == 0 {
 		p.errorf("vector selector must contain label matchers or metric name")
 	}
+	// A vector selector must contain at least one non-empty matcher to prevent
+	// implicit selection of all metrics (e.g. by a typo).
+	notEmpty := false
+	for _, lm := range matchers {
+		// Matching changes the inner state of the regex and causes reflect.DeepEqual
+		// to return false, which break tests.
+		// Thus, we create a new label matcher for this testing.
+		lm, err := metric.NewLabelMatcher(lm.Type, lm.Name, lm.Value)
+		if err != nil {
+			p.error(err)
+		}
+		if !lm.Match("") {
+			notEmpty = true
+			break
+		}
+	}
+	if !notEmpty {
+		p.errorf("vector selector must contain at least one non-empty matcher")
+	}
 
 	var err error
 	var offset time.Duration

promql/parse_test.go

@@ -587,6 +587,22 @@ var testExpr = []struct {
 		input:  `{}`,
 		fail:   true,
 		errMsg: "vector selector must contain label matchers or metric name",
+	}, {
+		input:  `{x=""}`,
+		fail:   true,
+		errMsg: "vector selector must contain at least one non-empty matcher",
+	}, {
+		input:  `{x=~".*"}`,
+		fail:   true,
+		errMsg: "vector selector must contain at least one non-empty matcher",
+	}, {
+		input:  `{x!~".+"}`,
+		fail:   true,
+		errMsg: "vector selector must contain at least one non-empty matcher",
+	}, {
+		input:  `{x!="a"}`,
+		fail:   true,
+		errMsg: "vector selector must contain at least one non-empty matcher",
 	}, {
 		input:  `foo{__name__="bar"}`,
 		fail:   true,

promql/testdata/legacy.test

@@ -378,7 +378,7 @@ eval instant at 50m drop_common_labels(http_requests{group="production",job="api
 	http_requests{instance="0"} 100 
 	http_requests{instance="1"} 200 
 
-eval instant at 50m {__name__=~".*"}
+eval instant at 50m {__name__=~".+"}
 	http_requests{group="canary", instance="0", job="api-server"} 300 
 	http_requests{group="canary", instance="0", job="app-server"} 700 
 	http_requests{group="canary", instance="1", job="api-server"} 400 

web/api/v1/api_test.go

@@ -277,7 +277,7 @@ func TestEndpoints(t *testing.T) {
 		}, {
 			endpoint: api.dropSeries,
 			query: url.Values{
-				"match[]": []string{`{__name__=~".*"}`},
+				"match[]": []string{`{__name__=~".+"}`},
 			},
 			response: struct {
 				NumDeleted int `json:"numDeleted"`